There are many processes which allow for the application of material across the transverse width of a web. However, many of these processes accomplish this feat at the cost of affecting the speed of the entire web.
An example of modifying the speed of only a portion of the web as opposed to modifying the speed of the entire web is shown in U.S. Pat. No. 5,693,165 issued to Schmitz. The Schmitz reference teaches that a pair of translatable transport rollers may be used in conjunction with a pair of stationary guide rollers to affect a velocity change in a portion of the web. The transport rollers are mounted on a sled which is periodically translated along a frame. Because the web is looped around the translatable transport rollers, as the sled translates along the frame in the direction of web feed, the web portion between the two translatable transport rollers has a velocity which is less than that of the overall web velocity. Therefore, a process could be implemented wherein a material is placed onto the portion of the web having a reduced velocity.
European Patent Application EP-A-0 364 087 discloses an applicator device for applying layers of material generally transversely across an elongated web. The elongated web moves continuously through the device in a web feed direction at a predetermined web speed. The device comprises two transport members which each turn the web 90 degrees in the plane of the web. The web portion between the two transport members is of constant length and extends perpendicular to the upstream portion of the web. The transport members are mounted on a sled which translates in the web feed direction and the reverse web feed direction. When the sled translates in the web feed direction at a speed which equals the web speed, the web portion between the transport members is stationary relative to the frame. A rotating applicator wheel having a tangential speed, which equals the linear speed of the air bars, can contact the web portion to attach a layer of material. When the frame is translated in the reverse web feed direction, the web portion is accelerated past the transport members to the web's downstream side.
From European Patent application EP-A-0 284 652 it is known to supply tensioned elastic ribbons transversely to a continuously moving web at a high speed. A number of applicator heads are mounted on a rotatable vertical shaft with each applicator head being connected to a radial arm. Upon rotation of the shaft, the arms pass over the moving web. At the position when a radial arm extends perpendicular to the web and has a tangential velocity equal to the linear web speed, a pre-stretched elastic is fed from the applicator head. A rotating anvil, which has a circumferential velocity equal to the linear web speed to minimize the shearing forces, contacts the applicator head upon attachment of the elastic.
Because the above apparatus has multiple arms, it can attach transverse parts to the moving web at a high speed and exert a low tension on the web with the web speed remaining constant. But, the application of complex parts in a transverse orientation to the web may require momentarily stopping the web at the position of the applicator device. In this instance, the above apparatus is less suitable.
It is an object of the present invention to provide a method by which a material may be applied to a moving web transversely without affecting the overall processing speed of the web regardless of the complexity of the material to be applied to the web.